ATM S 111, Global Warming: Understanding the Forecast

1. ATM S 111, Global Warming: Understanding the Forecast Dargan M. W. Frierson Department of Atmospheric Sciences Day 1: March 30, 2010

2. About Me • Professor: Dargan Frierson • Home town: Wilmington, NC • Southeastern North Carolina, on the coast

3. About Me Home town: Wilmington, NC Wilmington, NC Hurricane Fran, 1996

4. About Me Home town: Wilmington, NC Wilmington, NC Hurricane Floyd, 1999

5. About Me Home town: Wilmington, NC Wilmington, NC Hurricane Bertha, 1996

6. About Me Home town: Wilmington, NC Wilmington, NC Hurricane Diana, 1984

7. About Me Home town: Wilmington, NC Wilmington, NC Hurricane Bonnie, 1998

8. About Me Undergraduate: North Carolina State, Raleigh, NC Raleigh, NC Total precipitation from Hurricane Fran, 1996 (my freshman year)

9. After Grad School • Grad school at Princeton (applied math) • Postdoc (2 yrs) at University of Chicago • Assistant professor at UW starting 2007 • I love teaching! • Especially at the undergraduate and introductory level • I’ve taught Climate Dynamics, Modeling the Atmosphere, Atmospheric Motions, Geophysical Fluid Dynamics, Atmospheric Waves and Instabilities, etc • Active in creating YouTube videos for Outreach

10. Teaching • Two TAs in this class • Yurong Luan • Studies atmospheric chemistry • Chris Terai • Studies clouds and climate

11. Goals of the Class • We’re going tolearn about: • The science behind global warming • The role of science in formulating effective societal responses • How to critically evaluate what you hear about climate and global warming • Related issues such as energy alternatives

12. Class Outline Weeks 1-2: Overview and global warming science Weeks 3-4: Impacts of climate change Weeks 5-6: Climate records, long ago and recent past Weeks7: Climate modeling and future projections Week 8: The debate Week 9: Solutions Week 10: Economics and politics

13. Required Course Materials • The Rough Guide to Climate Change, 2nd edition by Robert Henson • Additional articles on class website • “Clickers” for in-class questions and activities • Check UW Classifieds (link from course homepage) for used clickers

14. Grading Comprehensive final: 25% Quizzes (3): 40% Homework: 20% In-class activities: 15% Extra credit: up to 5%

15. “Quiz” Sections • Actually for discussion and review • Includes problem solving • In class activities for points (no clickers needed) • Don’t switch sections (there’s only room for 30 students in each) • There has been one room change: • Section “10624 AF”  (one of the Thursday 1:30-2:20 sections) is now meeting in ATG310C

16. Course Webpage http://www.atmos.washington.edu/~dargan/111.html Check it often! It’ll have all reading assignments, links to the HW, slides from lectures, etc

17. Homework Online using moodle (link will be posted on the class website once the first assignment is ready) Use Firefox browser and UWIN ID Enrollment key:albedo(needed first time only) OK to discuss problems with classmates, but turn in your own answers

18. Clicker Questions Half credit for wrong answers Full credit for right answers or survey questions Use only your own clicker

19. Extra Credit • Send me questions. If they get asked in class, you get 0.5 points extra credit • Either questions about the material (“Ask the Professor”) • Or good survey questions (“Ask the Audience”) • I’ll do a couple of each during every class

20. Other Ground Rules • Respect! • This can be a politically charged topic: respect your neighbor’s views • No texting, e-mails, etc • We’ll take a 10 minute break each class period

21. First… • Abasic summary of the science of global warming • Reading assignment for the summary: • Rough Guide p. 3-19, “Climate Change: A Primer” • If it’s about restaurants in Prague, you’ve probably got the wrong Rough Guide

22. The Atmosphere From Space

23. Weather versus Climate • Weather varies from one day to the next • Climate: averages of the weather over a longer period of time • Examples: • Today was 50 andrainy: weather • This winter was drier than usual: climate • Can we predict each of these examples? • Yes!

24. What Factors Influence Climate? • Sunshine • And relatedly, latitude • Topography/mountains • Proximity to oceans and large lakes • Ocean currents • Presence of trees/vegetation • Etc.

25. The atmosphere from space… 90% of the mass of the atmosphere is within 16 km (10 miles) Distance from equator to pole = 10,000 km Relatively speaking, the atmosphere is about half as thin as typical seams on a basketball It’s remarkably thin…

26. We Modify the Composition of the Atmosphere Carbon dioxide (CO2) has been measured at Mauna Loa, Hawaii since 1958 “Keeling curve”: first measured by David Keeling in March ’58 ~ 25% increase since the first measurement Human induced: Due to fossil fuel burning (80%) and deforestation (20%)

27. Let’s Look Way Back to 450,000 Years We’re at 387 ppmnow Natural variation over Ice Age Cycles: 180-280 ppm Current rate of increase is 100-1000 times faster than nature can change CO2 280 180 Imgsrc: Global Warming Art Past Present

28. CO2is a Greenhouse Gas • Greenhouse gases slow heat loss to space • Has been known for a long time (J. Fourier in 1824) This is why it’s hot The Sun heats the Earth. Greenhouse gases cause the Earth to be a lot warmer than if there was no atmosphere: 58o F or 32o C warmer The natural greenhouse effect Joseph Fourier

29. The Earth is Warming MoreCO2 -> warmer atmosphere (eventually) Has it been getting warmer? It’s warmed about 0.8o C (1.5o F) in the last 130 years Especially rapid warming since the mid-’70s 9 out of the top 10 hottest years on record were the last 9 years 1o F 0.5o F 0o F -0.5o F Src: NASA GISS

30. Warming has happened almost everywhere. Northern high latitudes have warmed the most. Land has warmed more than ocean. Src: IPCC AR3

31. Hasn’t This Data Been Faked? No, we’re confident about the thermometer data Recent controversy has been about tree ring reconstructions (known as the “hockey stick”): 1o F This is much less certain, and only represents the Northern Hemisphere anyway (gray area indicates uncertainty). We’ll discuss this and other controversies more later… 0o F -1o F -2o F Src: IPCC AR3

32. What Else is Happening? • As temperatures rise  • Sea level is rising  20 cm = 8 inches • Snow cover is decreasing  Also glaciers are melting, Arctic sea ice is melting, species are shifting, etc Src: IPCC AR4

33. Could the Sun be the Cause? No, the Sun is nearly the weakest it’s been in 30 years Sun is very weak now Solar output Deepest solar minimum in terms of sunspots in 100 years (more sunspots  slightly hotter Sun) Sunspot number 1975 Year 2010 In general, strength of solar variability isvery weak (0.1% from max to min)

34. What’s Predicted for the Future? • Best calculated with a climate model • There is uncertainty associated with these models • Also must take into account human behavior • Will we reduce emissions, or will we burn fossil fuels more and more rapidly? • How quickly will developing countries get rich? • Scenarios provided by economists, policy makers, etc: CO2 emissions Src: IPCC AR3 2100 2000

35. Scenarios The scenarios produce the followingCO2 values: • Cutting fossil fuel usage • means weavoid these • really highconcentrations • But even in “utopia” • scenario,CO2 will likely • increase much more than it • has already Same plot from before of CO2 over last 400,000 years

36. What’s Predicted for the Future? Uncertainty both in human behavior (colors) and climate feedbacks (shaded area around ) • Climate models are saying “you • ain’t seen nothin yet” • Business as usual would mean • 3-4o C (5.5-7o F) more warming • “Utopia”: 1.5-2o C (3-4o F) warming • Even if we kept presentCO2 levels, • there would still be a bit more warming 10o F 8o F 6o F 4o F 2o F 0o F Note scenario colors are different than on the previous slide… (sorry) Src: IPCC AR4

37. Controversy About All This? • No doubt about these things: • The greenhouse effect • ThatCO2 and other greenhouse gases are increasing • That increases inCO2 are due to man • Skeptics tend to argue for: • “Negative feedbacks” that keep the temperature changes small • Or that warming wouldn’t be such a bad thing • Or about flaws in a particular study • Be wary: • Much of “the debate” (on both sides) is not very scientific • Let’s sort out fact from fiction!

38. A Sampling of Future Topics • “Paleoclimate”: • Ice Ages and hot climates of the past like the Cretaceous Ice sheet extent Last Glacial Maximum Present The Cretaceous Seaway

39. Volcanoes and Climate How the Earth cools after certain types of volcanoes… Eruption of Mount Pinatubo in June 1991 and its effect on global temperatures

40. And Man-Made Volcanoes! • “Geoengineering”: using technology to cool the Earth • People are considering things like • Putting volcanic-type particles into the stratosphere • Space mirrors • Cloud machines • Fake trees Right picture from Rolling Stone article “Can Dr. Evil Save the World?”

41. The Effect of Climate on Nature Cute animal pictures!!

42. Climate and the Rainforests The effect of burning tropical rainforests on climate And the effect of climate change on rainforests Rainforests burning over the Brazil-Bolivia border Satellite photo from NASA (MODIS): Locations of fires marked by (enhanced) red dots

43. Winners and Losers • And who will it hurt the most? Who will benefit… New shipping lanes

44. Floods Floods in Yemen, October 2008

45. And Droughts… Lake Chad UNEP

46. Science and Policy • The ozone problem • This was solved by the most efficient interaction between science and policy to date ✕ Discovery of the ozone hole led to a ban on all CFCs Why is global warming so much more difficult from a policy perspective?

47. Let’s Get Started! First topic: the science of climate What are the key factors that determine the temperature of Earth?